From patchwork Thu Jul 10 02:37:30 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Saravana Kannan X-Patchwork-Id: 4520501 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id C11B5BEEAA for ; Thu, 10 Jul 2014 02:37:45 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 39FF020353 for ; Thu, 10 Jul 2014 02:37:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 97AD220351 for ; Thu, 10 Jul 2014 02:37:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751294AbaGJChk (ORCPT ); Wed, 9 Jul 2014 22:37:40 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:43537 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751232AbaGJChj (ORCPT ); Wed, 9 Jul 2014 22:37:39 -0400 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 3DB0113FC9A; Thu, 10 Jul 2014 02:37:38 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 486) id 2FB0013FD44; Thu, 10 Jul 2014 02:37:38 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from skannan1-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: skannan@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 2644213FD42; Thu, 10 Jul 2014 02:37:37 +0000 (UTC) From: Saravana Kannan To: "Rafael J . Wysocki" , Viresh Kumar , Todd Poynor Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, "Saravana Kannan" Subject: [PATCH] cpufreq: Don't destroy/realloc policy/sysfs on hotplug/suspend Date: Wed, 9 Jul 2014 19:37:30 -0700 Message-Id: <1404959850-11617-1-git-send-email-skannan@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Preliminary patch. Not tested. Just sending out to give an idea of what I'm looking to do. Expect a lot more simplification when it's done. Benefits: * A lot more simpler code. * Less stability issues. * Suspend/resume time would improve. * Hotplug time would improve. * Sysfs file permissions would be maintained. * More policy settings would be maintained across suspend/resume. * cpufreq stats would be maintained across hotplug for all CPUs. Change-Id: I39c395e1fee8731880c0fd7c8a9c1d83e2e4b8d0 Signed-off-by: Saravana Kannan --- drivers/cpufreq/cpufreq.c | 293 +++++++++------------------------------------- 1 file changed, 55 insertions(+), 238 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 62259d2..8ca1b6f 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -859,13 +859,13 @@ void cpufreq_sysfs_remove_file(const struct attribute *attr) } EXPORT_SYMBOL(cpufreq_sysfs_remove_file); -/* symlink affected CPUs */ +/* symlink related CPUs */ static int cpufreq_add_dev_symlink(struct cpufreq_policy *policy) { unsigned int j; int ret = 0; - for_each_cpu(j, policy->cpus) { + for_each_cpu(j, policy->related_cpus) { struct device *cpu_dev; if (j == policy->cpu) @@ -881,12 +881,16 @@ static int cpufreq_add_dev_symlink(struct cpufreq_policy *policy) return ret; } -static int cpufreq_add_dev_interface(struct cpufreq_policy *policy, - struct device *dev) +static int cpufreq_add_dev_interface(struct cpufreq_policy *policy) { struct freq_attr **drv_attr; + struct device *dev; int ret = 0; + dev = get_cpu_device(policy->cpu); + if (!dev) + return -EINVAL; + /* prepare interface data */ ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq, &dev->kobj, "cpufreq"); @@ -961,12 +965,13 @@ static void cpufreq_init_policy(struct cpufreq_policy *policy) } #ifdef CONFIG_HOTPLUG_CPU -static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, - unsigned int cpu, struct device *dev) +static int cpufreq_change_policy_cpus(struct cpufreq_policy *policy, + unsigned int cpu, bool add) { int ret = 0; unsigned long flags; + /* FIXME: Don't send START/STOP when going from/to 0 cpus */ if (has_target()) { ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP); if (ret) { @@ -979,7 +984,11 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, write_lock_irqsave(&cpufreq_driver_lock, flags); - cpumask_set_cpu(cpu, policy->cpus); + if (add) + cpumask_set_cpu(cpu, policy->cpus); + else + cpumask_clear_cpu(cpu, policy->cpus); + per_cpu(cpufreq_cpu_data, cpu) = policy; write_unlock_irqrestore(&cpufreq_driver_lock, flags); @@ -995,27 +1004,9 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, return ret; } } - - return sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq"); } #endif -static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu) -{ - struct cpufreq_policy *policy; - unsigned long flags; - - read_lock_irqsave(&cpufreq_driver_lock, flags); - - policy = per_cpu(cpufreq_cpu_data_fallback, cpu); - - read_unlock_irqrestore(&cpufreq_driver_lock, flags); - - policy->governor = NULL; - - return policy; -} - static struct cpufreq_policy *cpufreq_policy_alloc(void) { struct cpufreq_policy *policy; @@ -1076,22 +1067,6 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy) kfree(policy); } -static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu) -{ - if (WARN_ON(cpu == policy->cpu)) - return; - - down_write(&policy->rwsem); - - policy->last_cpu = policy->cpu; - policy->cpu = cpu; - - up_write(&policy->rwsem); - - blocking_notifier_call_chain(&cpufreq_policy_notifier_list, - CPUFREQ_UPDATE_POLICY_CPU, policy); -} - static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) { unsigned int j, cpu = dev->id; @@ -1111,55 +1086,28 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) #ifdef CONFIG_SMP /* check whether a different CPU already registered this * CPU because it is in the same boat. */ + /* FIXME: This probably needs fixing to avoid "try lock" from + * returning NULL. Also, change to likely() */ policy = cpufreq_cpu_get(cpu); if (unlikely(policy)) { + cpufreq_change_policy_cpus(policy, cpu, true); cpufreq_cpu_put(policy); return 0; } #endif + /* FIXME: Is returning 0 the right thing to do?! Existing code */ if (!down_read_trylock(&cpufreq_rwsem)) return 0; -#ifdef CONFIG_HOTPLUG_CPU - /* Check if this cpu was hot-unplugged earlier and has siblings */ - read_lock_irqsave(&cpufreq_driver_lock, flags); - list_for_each_entry(tpolicy, &cpufreq_policy_list, policy_list) { - if (cpumask_test_cpu(cpu, tpolicy->related_cpus)) { - read_unlock_irqrestore(&cpufreq_driver_lock, flags); - ret = cpufreq_add_policy_cpu(tpolicy, cpu, dev); - up_read(&cpufreq_rwsem); - return ret; - } - } - read_unlock_irqrestore(&cpufreq_driver_lock, flags); -#endif - - /* - * Restore the saved policy when doing light-weight init and fall back - * to the full init if that fails. - */ - policy = recover_policy ? cpufreq_policy_restore(cpu) : NULL; - if (!policy) { - recover_policy = false; - policy = cpufreq_policy_alloc(); - if (!policy) - goto nomem_out; - } - - /* - * In the resume path, since we restore a saved policy, the assignment - * to policy->cpu is like an update of the existing policy, rather than - * the creation of a brand new one. So we need to perform this update - * by invoking update_policy_cpu(). - */ - if (recover_policy && cpu != policy->cpu) - update_policy_cpu(policy, cpu); - else - policy->cpu = cpu; + /* If we get this far, this is the first time we are adding the + * policy */ + policy = cpufreq_policy_alloc(); + if (!policy) + goto nomem_out; + policy->cpu = cpu; cpumask_copy(policy->cpus, cpumask_of(cpu)); - init_completion(&policy->kobj_unregister); INIT_WORK(&policy->update, handle_update); @@ -1175,20 +1123,23 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) /* related cpus should atleast have policy->cpus */ cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus); + /* Weed out impossible CPUs. */ + cpumask_and(policy->related_cpus, policy->related_cpus, + cpu_possible_mask); + + /* Just make the first CPU in the policy as the permanent owner of + * the sysfs nodes. It doesn't need to be online to host the nodes */ + policy->cpu = cpumask_first(policy->related_cpus); + /* * affected cpus must always be the one, which are online. We aren't * managing offline cpus here. */ cpumask_and(policy->cpus, policy->cpus, cpu_online_mask); - if (!recover_policy) { - policy->user_policy.min = policy->min; - policy->user_policy.max = policy->max; - } - down_write(&policy->rwsem); write_lock_irqsave(&cpufreq_driver_lock, flags); - for_each_cpu(j, policy->cpus) + for_each_cpu(j, policy->related_cpus) per_cpu(cpufreq_cpu_data, j) = policy; write_unlock_irqrestore(&cpufreq_driver_lock, flags); @@ -1243,13 +1194,11 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) blocking_notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_START, policy); - if (!recover_policy) { - ret = cpufreq_add_dev_interface(policy, dev); - if (ret) - goto err_out_unregister; - blocking_notifier_call_chain(&cpufreq_policy_notifier_list, - CPUFREQ_CREATE_POLICY, policy); - } + ret = cpufreq_add_dev_interface(policy); + if (ret) + goto err_out_unregister; + blocking_notifier_call_chain(&cpufreq_policy_notifier_list, + CPUFREQ_CREATE_POLICY, policy); write_lock_irqsave(&cpufreq_driver_lock, flags); list_add(&policy->policy_list, &cpufreq_policy_list); @@ -1257,10 +1206,6 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) cpufreq_init_policy(policy); - if (!recover_policy) { - policy->user_policy.policy = policy->policy; - policy->user_policy.governor = policy->governor; - } up_write(&policy->rwsem); kobject_uevent(&policy->kobj, KOBJ_ADD); @@ -1307,161 +1252,43 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) return __cpufreq_add_dev(dev, sif); } -static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *policy, - unsigned int old_cpu) -{ - struct device *cpu_dev; - int ret; - - /* first sibling now owns the new sysfs dir */ - cpu_dev = get_cpu_device(cpumask_any_but(policy->cpus, old_cpu)); - - sysfs_remove_link(&cpu_dev->kobj, "cpufreq"); - ret = kobject_move(&policy->kobj, &cpu_dev->kobj); - if (ret) { - pr_err("%s: Failed to move kobj: %d\n", __func__, ret); - - down_write(&policy->rwsem); - cpumask_set_cpu(old_cpu, policy->cpus); - up_write(&policy->rwsem); - - ret = sysfs_create_link(&cpu_dev->kobj, &policy->kobj, - "cpufreq"); - - return -EINVAL; - } - - return cpu_dev->id; -} - -static int __cpufreq_remove_dev_prepare(struct device *dev, - struct subsys_interface *sif) +static int __cpufreq_remove_dev(struct device *dev, + struct subsys_interface *sif) { unsigned int cpu = dev->id, cpus; - int new_cpu, ret; + int ret; unsigned long flags; struct cpufreq_policy *policy; pr_debug("%s: unregistering CPU %u\n", __func__, cpu); - write_lock_irqsave(&cpufreq_driver_lock, flags); - + read_lock_irqsave(&cpufreq_driver_lock, flags); policy = per_cpu(cpufreq_cpu_data, cpu); - - /* Save the policy somewhere when doing a light-weight tear-down */ - if (cpufreq_suspended) - per_cpu(cpufreq_cpu_data_fallback, cpu) = policy; - - write_unlock_irqrestore(&cpufreq_driver_lock, flags); + read_unlock_irqrestore(&cpufreq_driver_lock, flags); if (!policy) { pr_debug("%s: No cpu_data found\n", __func__); return -EINVAL; } - if (has_target()) { - ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP); - if (ret) { - pr_err("%s: Failed to stop governor\n", __func__); - return ret; - } - } - - if (!cpufreq_driver->setpolicy) - strncpy(per_cpu(cpufreq_cpu_governor, cpu), - policy->governor->name, CPUFREQ_NAME_LEN); +#ifdef CONFIG_HOTPLUG_CPU + ret = cpufreq_change_policy_cpus(policy, cpu, false); + /* FIXME: Handle error */ +#endif + /* FIXME: This stuff below would get pulled into change_policy_cpus. + * Keeping it here just for the RFC diff to be easy to read. */ down_read(&policy->rwsem); cpus = cpumask_weight(policy->cpus); up_read(&policy->rwsem); - if (cpu != policy->cpu) { - sysfs_remove_link(&dev->kobj, "cpufreq"); - } else if (cpus > 1) { - new_cpu = cpufreq_nominate_new_policy_cpu(policy, cpu); - if (new_cpu >= 0) { - update_policy_cpu(policy, new_cpu); - - if (!cpufreq_suspended) - pr_debug("%s: policy Kobject moved to cpu: %d from: %d\n", - __func__, new_cpu, cpu); - } - } else if (cpufreq_driver->stop_cpu && cpufreq_driver->setpolicy) { + if (cpus < 1 && cpufreq_driver->stop_cpu && cpufreq_driver->setpolicy) { cpufreq_driver->stop_cpu(policy); } return 0; } -static int __cpufreq_remove_dev_finish(struct device *dev, - struct subsys_interface *sif) -{ - unsigned int cpu = dev->id, cpus; - int ret; - unsigned long flags; - struct cpufreq_policy *policy; - - read_lock_irqsave(&cpufreq_driver_lock, flags); - policy = per_cpu(cpufreq_cpu_data, cpu); - read_unlock_irqrestore(&cpufreq_driver_lock, flags); - - if (!policy) { - pr_debug("%s: No cpu_data found\n", __func__); - return -EINVAL; - } - - down_write(&policy->rwsem); - cpus = cpumask_weight(policy->cpus); - - if (cpus > 1) - cpumask_clear_cpu(cpu, policy->cpus); - up_write(&policy->rwsem); - - /* If cpu is last user of policy, free policy */ - if (cpus == 1) { - if (has_target()) { - ret = __cpufreq_governor(policy, - CPUFREQ_GOV_POLICY_EXIT); - if (ret) { - pr_err("%s: Failed to exit governor\n", - __func__); - return ret; - } - } - - if (!cpufreq_suspended) - cpufreq_policy_put_kobj(policy); - - /* - * Perform the ->exit() even during light-weight tear-down, - * since this is a core component, and is essential for the - * subsequent light-weight ->init() to succeed. - */ - if (cpufreq_driver->exit) - cpufreq_driver->exit(policy); - - /* Remove policy from list of active policies */ - write_lock_irqsave(&cpufreq_driver_lock, flags); - list_del(&policy->policy_list); - write_unlock_irqrestore(&cpufreq_driver_lock, flags); - - if (!cpufreq_suspended) - cpufreq_policy_free(policy); - } else if (has_target()) { - ret = __cpufreq_governor(policy, CPUFREQ_GOV_START); - if (!ret) - ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS); - - if (ret) { - pr_err("%s: Failed to start governor\n", __func__); - return ret; - } - } - - per_cpu(cpufreq_cpu_data, cpu) = NULL; - return 0; -} - /** * cpufreq_remove_dev - remove a CPU device * @@ -1475,10 +1302,7 @@ static int cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) if (cpu_is_offline(cpu)) return 0; - ret = __cpufreq_remove_dev_prepare(dev, sif); - - if (!ret) - ret = __cpufreq_remove_dev_finish(dev, sif); + ret = __cpufreq_remove_dev(dev, sif); return ret; } @@ -2295,19 +2119,12 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb, if (dev) { switch (action & ~CPU_TASKS_FROZEN) { case CPU_ONLINE: + case CPU_DOWN_FAILED: __cpufreq_add_dev(dev, NULL); break; case CPU_DOWN_PREPARE: - __cpufreq_remove_dev_prepare(dev, NULL); - break; - - case CPU_POST_DEAD: - __cpufreq_remove_dev_finish(dev, NULL); - break; - - case CPU_DOWN_FAILED: - __cpufreq_add_dev(dev, NULL); + __cpufreq_remove_dev(dev, NULL); break; } }